Parkinson's disease (PD) affects the control of posture and gait, and leads to falling which contributes to reduced activity, reduced quality of life, depression, social isolation and mortality. Most interventions involving use of visual or auditory sensory cues to improve posture and gait do not carry over from the clinic to everyday living, and performance returns to pre-intervention levels. The PIs'long-term objective is to overcome the shortcomings of retention of interventions with portable, mobile interactive assistive devices, delivering haptic cues to improve balance and mobility, particularly in the realm of gait initiation and freezing of gait in individuals with Parkinson's disease. Haptic cues from touch hold great potential in this arena because studies in healthy subjects show haptic cues engage postural reflexes to stabilize posture and require no learning. However, the use of haptic cues by individuals with PD is not understood in the context of posture and gait. Thus, the immediate objectives of the proposed research is to examine the clinical value of haptic cues on posture and gait, as well as examine mechanisms governing motor control using haptic cues. The specific aims are to test the hypotheses that haptic cues can ameliorate aspects of (1) posture and (2) gait control associated with PD and age-matched control subjects, and to characterize the temporal coordination of sensory-motor mechanisms in both subject groups that are engaged by these cues. The PIs propose (1) to compare amplitudes and timing of postural sway while standing as still as possible with vs. without non-supportive manual contact (<1 N) with a stationary surface, and (2) to compare gait parameters, stride-to-stride variance of gait parameters, and timing of EMG activity of unassisted walking vs. walking while using a unique "moving hand rail," that is touching the moving surface of a modified waist-high conveyor belt. Preliminary results suggest haptic cues are beneficial to posture and gait control of individuals with PD. Individuals with PD tested off medication using haptic cues without practice showed the same improvements in postural control and timing of postural responses as previously reported in healthy subjects. Walking while touching the moving hand rail increased stride length and cadence, and reduced stride length variability of individuals with PD on medication, compared to walking unassisted. The proposed experiments represent a beginning of a line of inquiry about the control of movement using haptic (implicitly, speed) cues, the results of which can be translated to the development of assistive aids to deliver haptic cues to control posture and gait for individuals with PD. Public Health Relevance: The proposed research will test the hypotheses that individuals with Parkinson's disease have better postural control when manually touching something stationary, and that their gait control is improved when walking while manually touching something moving at the desired walking speed. Outcomes of this research can establish a basis for designing a portable, mobile, interactive walking and balance assistive device to provide cues to enhance mobility and quality of life, and prevent falling in individuals with Parkinson's disease, as well as healthy older individuals.